Another point of uncertainty is whether there may be a difference between individual PPIs, with some pharmacodynamic studies suggesting an interaction with omeprazole but not with pantoprazole. The clinical evidence, however, is conflicting. There has been one clinical trial from Canada suggesting an interaction with omeprazole but not with pantoprazole. From a mechanistic view it is known that omeprazole is metabolized by the CYP219 enzyme, which converts clopidogrel into its active metabolite. And while pantoprazole can also be metabolized by this enzyme, it also uses other routes.